Grinding-bur.



J. H. LETZ.

GRINDING BUR.

APPLICATION FILE D JAN. 17. 1917.

1,2 14,513. -v Patented 001;. 30,1917.

| l 1n ill llll u I I .ill'"|||||||U||l|||||l||||||||||||| lllllll" muMILE-615565 E sTA'rEs PATENT JOHN HOLLAND LETZ, OF GROWN ?OIN'1 INDIANAASSIGNOR TO THE LETZ MANUFAC- TUBING COMPANY, OF CROWN POINT, INDIANA, ACORPORATION OF INDIANA.

GRIN DIN G-BUR.

Grinding-Burs, of which the following is a full, clear, and exactspecification.

My invention is concerned with grinding burs of the type shown in theLetz Patent No. 437,699, and is designed to produce a bur that willgrind more rapidly and economically-than can be done with the bur havingthe dress shown in the aforesaid patent.

To illustrate my invention, I annex hereto a sheet of drawings, in whichthe same reference characters are employed in all the figures, and inwhich,-

Figure 1 is a view of the complete face of the bur; V

Figi 2 is a section on the line 2-2 of Fig. 1; an

Fig. 3 is an enlarged view of the portion of the face shown in Fig. 1.

The body of the bur preferably consists of a thin annular casting, whichmay be reinforced on its back with one or more annular ribs r. Itsinding surface is generally flat, except as it is broken by the grindingribshereinafter described, which it will be understood are ordinarilycast integral with the body and ground off so as to form cutting edgesand grinding surfaces on all of them in the same plane, which edges andsurfaces are adapted to cofiperate with similar edges and surfacessimilarly formed on the similar ribs on the opposed face of thecompanion bur.

T e ribs are preferably arranged in groups, substantially triangular intheir eneral outline, and preferably six in numer. The ribs going tomake up each of the six groups preferably have the same design, orsubstantially so, so that description of one group will sufiice for,all.

Considering a central vertical line through Figs. 1 and 3 as the baseline for the purposes of description, the main ribs a, b, c, d and e areparallel to each other and extend at an angle of about sixty degrees tosaid base line. They are preferably interrupted, and thus made up of aplurality of sections, sue: as a, a, a a, b, b, b, b, a, c, 0 a7,

Specification of Letters Patent.

Application filed January 17, 1917. Serial 'No. 142,800.

a Patented Oct. so, 191?.

03', d e, e and 6 while the baflie ribs 7, g,

' h, j and 7c are preferably arranged in paralit", it, y, g, f, 7 9*,7c, is, k and k and are angular in their general design, the anglesbeing preferably right angles, and the angles of the alternate seriespointing in opposite directions. The various series of ribs of each ofthe sixty-degree sections begin at such a distance from the center ofthe disk as to leave the triangular plain spaces between each adjacentpair of sections thus facilitating the start of the centnfugal movementof the grain outward to the peripheries of the burs. In operation, thegrinding is mainly effected by the angular ribs 7, 71,, k, f, h, it,etc., while the angular ribs 9, y', g, etc., facing the other way aremainly ba e ri in their action, although they do some grinding.Similarly, the ribs a, b, 0, d, e, a, b, 0, d, e, etc., serve mainly toforce the grain being ground outward, although they too have someshearing action. The combined action of these three sets of ribs in thetwo burs produces a very eilicient grindmg apparatus for even sodifficult a substance as cotton seed.

What I claim as new, and desire to segure by Letters Patent of theUnited States, is:

1. A grinding bur consisting of a generally flat disk having a series ofgrinding ribs projecting therefrom and having their flat top surfaces inthe same plane and forming shearing edges, said ribs being arranged inplural series of parallel ribs separated by angular ribs having theirangles alternately facing in opposite directions.

2. grin 'ng bur consisting of a generally flat disk having a series ofgrinding '96 ribs projecting therefrom and having their flat topsurfaces in the same plane and form- JOHN HOLLAND LETZ.

Witnes:

[JOHN HowAnn MCELROY.

